Reliable communication may be essential in wireless networks, as the transmission medium may inherently lossy and susceptible to interference. To ensure reliable communication, the receiver may acknowledge every message that is received so that the sender may attempt to retransmit the messages if the acknowledgement is not received. This method of acknowledged communication may be implemented, for example, via unicast communication between a sender and a receiver.
It may be more efficient to send a single message rather than repeat the same message for every receiver node. Such a message sent from one sender to multiple receivers is sometimes referred to as a multicast message. Multicast message transmission may be achieved by forming multicast groups where every group consists of a subset of the network nodes that may be collectively addressed by a single address. The network nodes may be informed about the groups to which they belong and the respective multicast address. Broadcast, for example, may be considered to be a specific instance of multicast transmission in which the message is sent once to all the network nodes.
In multicast/broadcast communication, the multicast group address is used as the destination address. In order to ensure reliability, the sender may require receipt of acknowledgements from all the intended recipients. Efficient methods for acknowledgements to broadcast and multicast may be required for improved performance and reduced power consumption, especially, for example, in applications where power is scarce.
Several applications may require transmission of a message from one sender to many receivers (multicast or broadcast message). Acknowledged multicast communication may require multiple receivers to send acknowledgements to one receiver, which may result in several collisions and extended time durations to accomplish this.
In many applications a single message may be required to be sent to multiple or all network nodes. For example, in sensor networks, the configuration values for the sensors may be dynamically changed by sending a multicast/broadcast message. In temperature monitoring applications, the threshold value beyond which the sensor nodes report to the base station (BS) may be dynamically configured using multicast messages.
Several applications require transmission of a message from one sender to many receivers (multicast or broadcast message). Acknowledged multicast communication may require multiple receivers to send acknowledgements to one receiver, which may result in several collisions and extended time durations to accomplish this.